In X-ray imaging, for example in computed tomography, angiography, or radiography, counting direct-converting X-ray detectors can be used. The X-ray radiation or the photons can be converted into electric pulses by an appropriate sensor. CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr2, HgI2, GaAs or others can be used, for example, as a converter material for the sensor.
The energy of the incident ionizing radiation is directly converted into electrical charges, known as electron-hole pairs. A high voltage, for example, for CdTe, CZT, CdZnTeSe, CdTeSe or CdMnTe in the region of −500 to −2000V, is applied to the converter material between an electrode serving as a cathode and a readout contact serving as an anode, in order to separate the charges of the electron-hole pairs triggered in the converter material. The high voltage is applied to the electrode via an external high voltage source by way of an electrically conductive contact.
The sensor is generally connected in a planar manner in a stacked array with a readout and/or an evaluation unit, for example, to an integrated circuit (an Application Specific Integrated Circuit, ASIC), via soldered connections, electrically conductive adhesive, or other methods. The electric pulses are evaluated by an evaluation unit, an ASIC for example. The stacked array comprising the sensor and the integrated circuit is connected to a further substrate, for example a printed circuit board, a ceramic substrate such as, for example, HTCC or LTCC, or others. The electrical connections for reading out from the readout and/or the evaluation unit can be designed as through connections (through-silicon via, TSV) or wire bonds.
DE 10 2012 213 410 B3 discloses a direct-converting X-ray radiation detector, which comprises at least one electrode mounted on a semiconductor. The at least one electrode and the semiconductor are electrically conductively connected, the at least one electrode being designed to be transparent and electrically conductive.
U.S. Pat. No. 8,093,535 B2 discloses a circuit incorporated in a semiconductor material in order to measure signals from the sensor assigned to the integrated circuit. In at least one embodiment, the circuit comprises an active component, a temperature sensor, and a circuit to control the temperature of the semiconductor material. The active component is designed to process measuring signals produced by the sensor. The active component is intended to be controlled by the circuit in an activatable manner around the temperature, such that the temperature of the semiconductor material is variable. The circuit further comprises at least one of a PI- and PID-regulator in order to control the temperature.
U. S. 2003/0168605 A1 discloses a radiation detector having at least one semi-conductive connection, the semiconductive connection being designed to generate electron-hole pairs through the detection of radiation and the semiconductive connection being wired in a photovoltaic mode of operation. The detector has means for operating and maintaining the connection at an almost constant temperature.
DE 100 34 262 C1 discloses a semiconductor device, wherein an integrated circuit runs dummy work cycles in order to generate heat if the temperature of the semiconductor device drops below a lower limiting value.
DE 101 38 913 A1 discloses a detector module for X-ray computer tomographs, wherein a sensor array comprising a plurality of sensor elements is mounted on the front of a printed circuit board. To increase the accuracy of the detector, provision is made according to the invention on the back of the printed circuit board, which faces away from the sensor array, for at least one heating element to be provided to heat the sensor array and for an electronic control unit arranged in the vicinity of the heating element to control the heating element.